Methods of Cooling a Fluid Using an Annular Heat Exchanger

ABSTRACT

Methods of cooling a hot fluid in an annular duct of a gas turbine engine are provided. The method can include directing the hot fluid through a plurality of cooling channels that are radially layered within the annular duct to define a heat transfer area, and passing a cooling fluid through the annular duct such that the cooling fluid passes between the radially layered cooling channels. Additionally or alternatively, the method can include passing the hot fluid into a first inner radial tube, through a plurality of cooling channels defined within a plurality of curvilinear plates that are radially layered within the annular duct, and into a second inner radial tube; and passing a cooling fluid through the annular duct.

FEDERALLY SPONSORED RESEARCH

This invention was made with government support under contact numberN00014-10-D-0010 of the Department of the Navy. The government may havecertain rights in the invention.

FIELD OF THE INVENTION

The present invention relates generally to gas turbine engines and, moreparticularly, to a heat exchange arrangement in a fan duct of a gasturbine engine for cooling high pressure hot bleed air.

BACKGROUND OF THE INVENTION

Many commercial aircraft gas turbine engines employ high pressure hotair bled from the core engine compressor for use by different systems onthe aircraft. In particular, the high pressure air is required by avariety of tasks on the aircraft, such as anti-icing and passenger cabincooling. However, prior to use of the air, the temperature of the airmust be lowered to reasonable levels in accordance with the requirementsof each specific task.

One current method of cooling the high pressure compressor bleed air isto extract or bleed air from the engine fan duct imbedded within theengine case. The cooler bleed air from the fan duct and the highpressure hotter bleed air from the core engine compressor are thenpassed through a heat exchanger where the hotter high pressure air givesup some of its thermal energy to the cooler fan duct bleed air.

Use of the heat exchange process is necessary, although, current systemsfor attaining heat transfers are unduly complex. In one system, anelaborate layout of piping is employed to pass the high pressure bleedair to the aircraft and to route the cooler fan duct bleed air to thelocation of the heat exchanger. By the time the cooler fan duct bleedair reaches the heat exchanger and performs its cooling task, it haslost most of its pressure (thrust potential) due to frictional lossesbecause of various bends and turns of the piping. After exiting from theheat exchanger, the fan duct bleed air is discharged overboard from theaircraft structure with a negligible thrust benefit. The impact of thefan duct bleed air thrust loss on engine specific fuel consumption issignificant. Furthermore, the excessively complex bleed air piping addssignificantly to the aircraft weight.

Consequently, a need still remains for improvements in the arrangementfor performing heat transfer operations which will avoid the fan ductbleed air loss experienced by the prior art.

BRIEF DESCRIPTION OF THE INVENTION

Aspects and advantages of the invention will be set forth in part in thefollowing description, or may be obvious from the description, or may belearned through practice of the invention.

A curvilinear plate is generally provided. In one embodiment, thecurvilinear plate includes an inner plate defining a plurality of firstgrooves and an outer plate defining a plurality of second grooves. Theouter plate is attached to the inner plate with the plurality of firstgrooves and the plurality of second grooves substantially aligned todefine a plurality of channels therebetween. Each channel extends from afirst opening on a first portion of a first end of the curvilinear plateto a second opening on a second portion of the first end.

A method is also generally provided for forming a curvilinear plate. Inone embodiment, the method includes stamping a first sheet of metal toform a first plate defining a plurality of first grooves; stamping asecond sheet of metal to form a second plate defining a plurality ofsecond grooves; and thereafter, laminating the first sheet to the secondsheet to form the curvilinear plate such that the plurality of firstgrooves and the plurality of second grooves substantially aligned todefine a plurality of channels therebetween. Each channel extends from afirst opening on a first portion of a first end of the curvilinearplate, through a curve defined in each channel, and to a second openingon a second portion of the first end.

A transduct segment is also generally provided. In one embodiment, thetransduct segment includes a main tube extending from a first end to asecond end and defining a hollow passageway therethrough, a lowerplatform attached to an outer surface of the main tube on first side ofan aperture defined within the main tube, and an upper platform attachedto the outer surface of the main tube on second side of the aperturethat is opposite of the first side. The upper platform is integral withthe lower platform to define a supply channel therebetween, and thesupply channel is in fluid communication with the hollow passageway ofthe main tube through the aperture defined by the main tube. The lowerplatform and the upper platform define an interface defining a pluralityof channels in fluid communication with the hollow passageway defined bythe main tube.

In one embodiment, an annular heat exchanger is generally provided for agas turbine engine. The annular heat exchanger can include a firstannular ring comprising a first main tube defined by a plurality oftransduct segments; a second annular ring comprising a second main tubedefined by a plurality of transduct segments (such as described above)and a curvilinear plate defining at least one channel therein that is influid communication with a transduct segment of the first main tube anda transduct segment of the second main tube.

Methods are also generally provided of cooling a hot fluid in an annularduct of a gas turbine engine. In one embodiment, the method includesdirecting the hot fluid through a plurality of cooling channels that areradially layered within the annular duct to define a heat transfer area,and passing a cooling fluid through the annular duct such that thecooling fluid passes between the radially layered cooling channels.Additionally or alternatively, the method can include directing the hotfluid through a plurality of cooling channels that are radially layeredwithin the annular duct to define a heat transfer area, and passing acooling fluid through the annular duct such that the cooling fluidpasses between the radially layered cooling channels. Additionally oralternatively, the method can include passing the hot fluid into a firstinner radial tube, through a plurality of cooling channels definedwithin a plurality of curvilinear plates that are radially layeredwithin the annular duct, and into a second inner radial tube; andpassing a cooling fluid through the annular duct.

These and other features, aspects and advantages of the presentinvention will become better understood with reference to the followingdescription and appended claims. The accompanying drawings, which areincorporated in and constitute a part of this specification, illustrateembodiments of the invention and, together with the description, serveto explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof, directed to one of ordinary skill in the art, is setforth in the specification, which makes reference to the appended Figs.,in which:

FIG. 1 shows an exemplary annular heat exchanger according to oneembodiment for a gas turbine engine;

FIG. 2 shows a radial cross-sectional view of the exemplary annular heatexchanger of FIG. 1;

FIG. 3 shows a circumferential cross-sectional view of the exemplaryannular heat exchanger of FIG. 1;

FIG. 4 shows the radial cross-sectional view of the exemplary annularheat exchanger of FIG. 2 from an inner view;

FIG. 5 shows a close-up view of an interface of a transduct segmentattached to an end of a curvilinear plate;

FIG. 6 shows a circumferential cross-sectional view of exemplarytransduct segments that are fluidly connected along their main tube;

FIG. 7 shows an exemplary transduct segment defining a main tube and aninterface;

FIG. 8 shows a circumferential cross-sectional view of the exemplarytransduct segment of FIG. 7;

FIG. 9 shows a plurality of transduct segments as in FIG. 7, withadjacent transduct segments being fluidly connected along the main tube;

FIG. 10 shows an exemplary curvilinear plate defining a plurality ofchannels extending from a first opening on a first portion of a firstend of the curvilinear plate, through a curve defined in each channel,and to a second opening on a second portion of the first end;

FIG. 11 shows another view of the exemplary curvilinear plate of FIG.10;

FIG. 12 shows a close-up view of one portion of the first end of theexemplary curvilinear plate of FIGS. 10 and 11; and

FIG. 13 shows a cross-sectional view of one embodiment of a gas turbineengine that may include an exemplary annular heat exchanger according toone embodiment.

Repeat use of reference characters in the present specification anddrawings is intended to represent the same or analogous features orelements of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference now will be made in detail to embodiments of the invention,one or more examples of which are illustrated in the drawings. Eachexample is provided by way of explanation of the invention, notlimitation of the invention. In fact, it will be apparent to thoseskilled in the art that various modifications and variations can be madein the present invention without departing from the scope or spirit ofthe invention. For instance, features illustrated or described as partof one embodiment can be used with another embodiment to yield a stillfurther embodiment. Thus, it is intended that the present inventioncovers such modifications and variations as come within the scope of theappended claims and their equivalents.

As used herein, the terms “first”, “second”, and “third” may be usedinterchangeably to distinguish one component from another and are notintended to signify location or importance of the individual components.

The terms “upstream” and “downstream” refer to the relative directionwith respect to fluid flow in a fluid pathway. For example, “upstream”refers to the direction from which the fluid flows, and “downstream”refers to the direction to which the fluid flows.

As used herein, a “fluid” may be a gas or a liquid. The present approachis not limited by the types of fluids that are used. In the preferredapplication, the cooling fluid is fan air, and the cooled fluid is bleedair. However, the present approach may be used for other types of liquidand gaseous fluids, where the cooled fluid and the cooling fluid are thesame fluids or different fluids. Other examples of the cooled fluid andthe cooling fluid include air, hydraulic fluid, combustion gas,refrigerant, refrigerant mixtures, dielectric fluid for cooling avionicsor other aircraft electronic systems, water, water-based compounds,water mixed with antifreeze additives (e.g., alcohol or glycolcompounds), and any other organic or inorganic heat transfer fluid orfluid blends capable of persistent heat transport at elevated or reducedtemperature.

Heat exchangers are generally provided that includeperformance-enhancing geometries whose practical implementations arefacilitated by additive manufacturing. Although the heat exchangersystem described herein is broadly applicable to a variety of heatexchanger applications involving multiple fluid types, it is describedherein for its high-effectiveness cooling of bleed air (e.g., the hotstream) with fan air (e.g., the cold stream) in a gas turbine engine. Itshould be noted that although the present description relates to heatexchangers that are used in high by-pass turbine engines, one ofordinary skill in the art would understand that the description is notlimited to being used in high by-pass turbine engines. Rather, theprovided heat exchangers may be used in any engine and/or apparatusrequiring heat exchange. The heat exchangers are generally provided fora turbine engine that is coupled to at least one of a fan casing and anengine casing of the turbine engine. In an exemplary embodiment, theheat exchanger includes an annularly shaped body.

Referring to FIGS. 1-4, an annular jet engine air duct 10 is shown for agas turbine engines, such as turbofan, turboprop, and turbojet engines.The annular jet engine air duct 10 includes an annular heat exchanger 12formed from a first annular ring 14, a second annular ring 16, and aplurality of curvilinear plates 100 fluidly connecting the first annularring 14 to the second annular ring 16. The first annular ring 14 has afirst main tube 15 defined by a plurality of transduct segments 20connected in series to each other such that at least a portion ofadjacent transduct assemblies 20 are fluidly connected along the firstmain tube 15. Similarly, the second annular ring 16 has a second maintube 17 defined by a plurality of transduct segments 20. A curvilinearplate 100 defines at least one channel 110 that is in fluidcommunication with a transduct segment 20 of the first main tube 15 anda transduct segment 20 of the second main tube 17. The hot fluid (e.g.,bleed air) can pass through the at least one channel 102 of thecurvilinear plate 100 for heat transfer with a cooling fluid passingover the curvilinear plate 100. As shown, the curvilinear plate 100defines a curved surface that is oriented radially inward. However, inalternative embodiments, the curvilinear plate 100 can define a curvethat is oriented radially outward.

The plurality of curvilinear plates 100 are radially layered so as todefine a gap between adjacent curvilinear plates 100 through which thecooling fluid (e.g., fan air) can flow in the axial direction. In oneembodiment, the plurality of curvilinear plates 100 are generallyoriented in a uniform manner circumferentially around the annular ductsuch that the cooling fluid flow is forced to impinge on the curvilinearplates 100 (for heat transfer therethrough) without finding anysignificant alternative path. Thus, most of the hot fluid flows throughthis heat transfer area of the annular duct (i.e., within the gapsdefined between the inner band and the outer band with the radiallylayered plates therein). For example, at least 90% of the cooling fluidflows through the heat transfer area of the annular duct, such as atleast 95% (e.g., at least 99%). As such, the capture rate of the coolingfluid flow is maximized to increase the efficiency of the heat transferrate.

As shown, the first annular ring 14 is generally adjacent to andparallel with the second annular ring 16. However, in other embodiments,the first annular ring 14 and the second annular ring 16 can be shapeddifferent from one another and/or oriented in nonparallel manner.

In the embodiment shown, each of the first main tube 15 of the firstannular ring 14 and the second main tube 17 of the second annular ring16 is partitioned into multiple, independent sections 22, 23,respectively. Each of the independent sections 22, 23 is formed from aplurality of transduct segments 20 forming individual cavities throughthe respective first main tube 15 and second main tube 17. Theindependent sections 22, 23 are separated at boundary walls 24 withinthe end transduct segment 20 of the multiple, independent sections 22,23. Each transduct segment 20 spans, in particular embodiments, about 5°to about 20° of the circumferential length of the annular ring 14, 16.However, the transduct segment 20 can be formed to any desired lengthand/or shape.

Supply tubes 26 are shown within each section 22, 23 of the first maintube 15 and the second main tube 17, respectively, for supplying a fluidthereto. For example, the fluid can be compressed air for cooling (e.g.,bleed air from the engine). In the embodiment shown, the supply fluid 30(e.g., hot air) is introduced into the second annular ring 16 throughthe inlet supply tube 28, is passed from the second main tube 17 througha channel 110 of a curvilinear plate 100 (discussed below) into thefirst main tube 15, and exits through the outlet tube 32 as a cooledfluid 34. Specifically, a cooling fluid 36 (e.g., fan air) passesthrough the air duct 100 between the annular rings 14, 16 and theradially outer wall 40. It should be understood that the flow directionof either fluid can be changed as desired.

As discussed in greater detail below, the curvilinear plates 100 allowfor thermal transfer between the hotter, higher pressure fluid thereinand the cooler, lower pressure fluid passing through the duct. This heattransfer is enhanced by the geometries of the curvilinear plates 100,which have increased surface area available for heat transfer.

As more particularly shown in FIGS. 6-9, each transduct segment 20generally includes a main tube 200 extending from a first end 202 to asecond end 204 and defining a hollow passageway 206 therethrough.Adjacent transduct segments 20 are in fluid communication with eachother along the main tube 200 through attachment at respective endsthereof. That is, the first end 202 of one transduct segment 20 isattached to the second end 204 of an adjacent transduct segment 20. Asmore particularly shown in FIG. 8, a male insert 240 is defined by thesecond end 204 and a female cavity is defined within the first end 202to allow a male-female connection between adjacent transduct segments20. However, any other suitable connection mechanism can be utilized(e.g., braze, weld, o-ring, bolts, etc.).

The main tube 200 also defines at least one aperture 208 that is influid communication with a supply channel 210 defined between a lowerplatform 212 attached to an outer surface 214 of the main tube 200 onfirst side 216 of the aperture 208 and an upper platform 218 attached tothe outer surface 214 of the main tube 200 on second side 220 of theaperture 218 that is opposite of the first side 216. As such, the supplychannel 210 is in fluid communication with the hollow passageway 206 ofthe main tube 200 through the aperture 208 defined by the main tube 200.A plurality of apertures 218 are shown defined in the main tube 200 withan elongated shape in the annular direction. That is, the apertures 218may have a maximum length in an annular direction (i.e., that extendsfrom the first end of the main tube to the second end of the main tube)that is greater than a maximum width in a perpendicular direction to theannular direction (i.e., the axial direction).

In the embodiment shown, the main tube 200 defines an ellipsoidalcross-section at both the first end 202 and the second end 204. Forexample, the ellipsoidal cross-section can have a maximum width that isabout 1.5 times to about to about 20 times its maximum height. Such aellipsoidal shape allows for minimal resistance to the cooling fluid(e.g., fan air) passing through the duct 100. However, the main tube canhave other cross-sectional shapes, as desired.

In one embodiment, the upper platform 218 is integral with the lowerplatform 212 to define the supply channel 210 therebetween.Additionally, the upper platform 218 and the lower platform 212 can beintegral with the main tube 200 so as to form a single unitarycomponent. For example, the transduct segment 20 can be formedintegrally together via additive manufacturing process, and may beformed from additive materials including but not limited to titanium,titanium alloys, aluminum, aluminum alloys, and austenite alloys such asnickel-chromium-based superalloys (e.g., those available under the nameInconel® available from Special Metals Corporation).

At its terminal end 221 (opposite of the aperture 208 at the main tube200), the lower platform 212 and the upper platform 218 define aninterface 222 defining a plurality of channels 224 in fluidcommunication with the hollow passageway 206 defined by the main tube200. In one embodiment, a diverging angle 0 is defined between anuppermost tangent line 226 extending from the second end 204 of theouter surface 214 of the main tube 200 and a tangent line 228 extendingfrom the inner surface 213 of the lower platform 212, and wherein thediverging angle is about 10° to about 30°.

In the embodiment shown, the inner surface 230 of the lower platform 212defines a plurality of lower grooves 232 at the interface 222, and theinner surface 234 of the upper platform 218 defines a plurality of uppergrooves 238 at the interface 222. The plurality of lower grooves 232 aregenerally aligned with the plurality upper grooves 236 to define theplurality of channels 224. Additionally, a slot 238 is defined betweenthe inner surface 230 of the lower platform 212 and the inner surface234 of the upper platform 218 at the interface 222. As shown, the slot238 extends through the plurality of channels 224 defined between theupper platform 218 and the lower platform 212 so as to receive the firstend 124 of the curvilinear plate 100 therein, as more particularly shownin FIG. 5. In one embodiment, the first end 124 of the curvilinear plate100 is positioned and attached to the interface within the slot via abraze, a weld, or any other suitable attachment mechanism. In theembodiment shown, each channel 234 defined in the interface 222 of thetransduct segment 200 is in fluid communication with a respectivechannel 110 of the curvilinear plate 100, as discussed in greater detailbelow.

Referring to FIG. 8, an internal beam 242 may be present, as shown, andpositioned between the upper platform 218 and the lower platform 212 andextending from the supply channel 210 to the interface 222 to define aplurality of passageways 244 corresponding to the respective channels110 of the curvilinear plate 100 at the interface 222 such that eachpassageway 244 is in fluid communication with one of the channels 110.Additionally, the beams 242 can provide a structural support between theupper platform 218 and the lower platform 212. In one embodiment, themain tube 200 defines a plurality of apertures 208 that are in fluidcommunication with a respective passageway 244 and, therefore, are influid communication with a respective channel 110 of the curvilinearplate 100.

Referring to FIGS. 2 and 4, the transduct segment 20 may further includea first wing 252 extending from a first side 251 of the main tube 200and configured for attachment to a frame of an engine (not shown). Also,the transduct segment may further include a second wing 254 extendingfrom a second side 253 of the main tube 200 that is opposite from thefirst side 251 and configured for attachment to a wing 254 of anadjacent transduct segment 200. Thus, the first wing 252 and the secondwing 254 extend in an axial direction of the maximum width of theellipsoidal cross-section, and allow adjacent rings, 14, 16 to beconnected together to form the annular heat exchanger 12. The secondwings 254 of the adjacent transduct segments 20 may be integral to eachother or connected to each other through an attachment mechanism (e.g.,screw, bolt, weld, braze, etc.).

FIGS. 10-12 show an exemplary curvilinear plate 100 that includes aninner plate 102 defining a plurality of first grooves 104 and an outerplate 106 defines a plurality of second grooves 108. Generally, theinner plate 102 is attached to the outer plate 106 with the plurality offirst grooves 104 and the plurality of second grooves 108 substantiallyaligned to define a plurality of channels 110 therebetween. Theembodiment of FIG. 11 includes an optional integral wall 112 positionedbetween the inner plate 102 and the outer plate 106 such that eachchannel 110 defines a first passageway 114 and a second passageway 116therein.

In one embodiment, the inner plate 102 and the outer plate 106, alongwith the optional integral wall 112, are joined together via diffusionbonding without the presence of any braze or other weld. However, anysuitable attachment can be utilized to join the inner plate 102 and theouter plate 106, including but not limited to adhesive bonding, welding,brazing, etc.

In the embodiment shown, each channel 112 extends from a first opening120 on a first portion 122 of a first end 124 of the curvilinear plate100, through a curve 126 defined in each channel 112, and to a secondopening 128 on a second portion 130 of the first end 124. As such, afluid passing through each channel 112 routs through the curvilinearplate from the first opening 120 of the first portion 122, around thecurve 126, and out of the second opening 128 of the second portion 130(or, vice versa, in the opposite direction from the second opening 128to the first opening 120). Thus, each of the channels 112 define anonlinear path having at least one curve 126 extending from the firstopening 120 to the second opening 128.

FIG. 12 shows each of the first grooves 104 and the second grooves 108having a substantially semi-ellipsoidal shape so as to define asubstantially ellipsoidal channel 110. This shape not only allows forincreased surface area within the channel 110 for heat transfer, butalso allows the first grooves 104 and the second grooves 108 to beformed from a stamping process from a sheet (e.g., a metal sheet). Inthe embodiment shown, each of the first grooves 104 has a maximumcross-sectional arc length that is about 1.5 to about 20 times itsmaximum chord length. Similarly, each of the second grooves 108 has amaximum cross-sectional arc length that is about 1.5 to about 20 timesits maximum chord length. However, other geometries can be utilized asdesired.

In one embodiment, the first grooves 104 and/or the second grooves 108can define a plurality of dimples or other surface features to agitatefluid flow within the channel 110 and to provide for increased surfacearea for thermal transfer.

The curvilinear plate 100 generally defines a curvature (i.e.,non-planar) path from the first end 124 to the second end 132. In theembodiment shown, the curvature is generally constant to define an arclength of a circle. However, in other embodiments, the curvilinear plate100 can have a non-uniform curvature (i.e., constant) that varies acrossthe outer plate 126, and may include curves, bends, joints, planarportions, etc. No matter the particular cross-sectional shape, the outerplate 126 defines a chord length measured as a shortest distance fromthe first end 124 to the second end 132, and the outer plate 126 definesan arc length measured across its outer surface 127 from the first end124 to a second end 132. Using the same starting and ending points (forthe chord length and the arc length), the arc length is about 105% toabout 150% of the chord length. That is, the arc length is about 1.05times to about 1.5 times the chord length. As such, the curvature of thecurvilinear plate 100 allows for more surface area for thermal transferthan would otherwise be present with a planar plate.

In the embodiment shown in FIGS. 10 and 11, a slot 134 is defined in thecurvilinear plate 100 in the first end 124 between the first portion 122and the second portion 130. Generally, the slot 134 allows for flexingof the curvilinear plate 100 between the first portion 122 and thesecond portion 130, which are attached to respective interfaces 222 ofthe transduct 200. Although shown having a substantially U-shape, theslot 134 can have any geometry desired. Similarly, each channel 110 isshown extending in a substantially U-shape from the first opening 120 onthe first portion 122 of the first end 124, around the slot 134 definedin the curvilinear plate 100, and to the second opening 128 on thesecond portion 130 of the first end 124. However, the channels 110 cantake any desired path within the curvilinear plate 100.

The inner plate 102 and the outer plate 106 can be formed from anysuitable material having the desired thermal transfer properties. Forexample, the inner plate 102 and the outer plate 106 can be constructedfrom titanium, titanium alloys, aluminum, aluminum alloys, and austenitealloys such as nickel-chromium-based superalloys (e.g., those availableunder the name Inconel® available from Special Metals Corporation).

Likewise, the integral wall 112 can be made of any suitable material,when present. In one embodiment, the integral wall 112 is made from arelatively high thermally conductive material so as to facilitatethermal transfer between the first passageway 114 and the secondpassageway 116 within a channel 110. For example, the integral wall canbe made of plated copper, titanium, titanium alloys, aluminum, aluminumalloys, and austenite alloys such as nickel-chromium-based superalloys(e.g., those available under the name Inconel® available from SpecialMetals Corporation). In most embodiments, the inner plate 102 and theouter plate 106 have a substantially equal thickness across eachrespective surface, although the grooves 104, 108, respectively may beslightly thinner than the flatter portion. In most embodiments, theinner plate 102 and the outer plate 106 have a thickness that is about400 μm to about 800 μm, independently. The integral wall 112, whenpresent, can have a thickness that is about 400 μm to about 800 μm.

The integral wall 112 can, in certain embodiments, define a plurality ofholes (e.g., slots or other apertures) to allow fluid flow between thefirst passageway 114 and the second passageway 116 within a channel 110.Alternatively or additionally, the integral wall 112 can define aplurality of dimples or other surface features to agitate fluid flowwithin the first passageway 114 and the second passageway 116 within achannel 110 and to provide for increased surface area for thermaltransfer therebetween.

As shown in FIGS. 10 and 11, at least one of the inner plate 102 and theouter plate 106 (or both) comprises at least one tab 140 extending fromthe second end 132 that is opposite of the first end 124. Referring toFIG. 3, the tab(s) 140 extend into a slot 42 defined within a casing 44of the annular heat exchanger 12. The casing 44 generally includes astructural support 46 and the radial outer wall 40. As such, eachcurvilinear plate 100 is supported structurally so that thermalexpansion of each curvilinear plate 100 relative to the annular duct isunrestrained in at least one direction. That is, each curvilinear plate100 may be attached only at the first and second portions 122, 130 ofthe first end 124 to allow thermal expansion along the length of thecurvilinear plate 100 extending away from the respective transductsegment 20, while also allowing flexing in the axial direction due tothe slot therebetween. The tab 140 allows for slight movement and/orexpansion while remaining generally in place without restricting suchmovement and/or expansion.

In the embodiment shown, the structural support 46 includes a firstannular ring 47, a second annular ring 49 parallel to the first annularring 47, and a plurality of crossbars 51 connecting the first annularring 47 to the second annular ring 49. The crossbars 51 can define acavity 53 for receiving at least one the tabs 140.

In the embodiment shown, at least one of the tabs 140 defines anaperture 142 for receiving an attachment piece (not shown) therethroughso as to secure the second end 132 to the structural support 46 throughan attachment piece (e.g., a bolt, screw, pin, or other attachmentmember). In some embodiments, at least one of the tabs 140 can beslideably positioned within a respective slot 42 defined within thestructural support 46 of the casing 44. For example, the attachmentpiece can secure the tab 140 within the slot 42 while allowing for somemovement therein (e.g., an elongated aperture can allow for movement inthe longer direction of the aperture). For example, a combination ofslideably positioned tabs 140 and secured tabs 140 can be utilized toallow for flexing and/or slight movement of the second end 132 of thecurvilinear plate 100, while substantially keeping it in position. Thus,the curvilinear plate 100 can move in relation to the casing, allowingfor thermal expansion, flexing, vibrational movement, or other slightmovements in use. It is noted that FIG. 10 shows an embodiment whereeach tab 140 defines an aperture 142 for receiving an attachment piecetherethrough, while the embodiment of FIG. 11 shows only the center tab140 defining an aperture 142 with the outer tabs 142 being configuredfor slot positioning without any securing attachment piece.

As stated, the curvilinear plate 100 can be formed via a stampingprocess. In one embodiment, the curvilinear plate 100 can be formed bystamping a first sheet of metal to form a first plate defining aplurality of first grooves; stamping a second sheet of metal to form asecond plate defining a plurality of second grooves; and thereafter,laminating the first sheet to the second sheet to form the curvilinearplate such that the plurality of first grooves and the plurality ofsecond grooves substantially aligned to define a plurality of channelstherebetween. In one embodiment, prior to laminating, an integral wallcan be positioned between the first sheet and the second sheet such thateach channel defines a first passageway and a second passageway therein.

In one embodiment, the annular duct is used in a method of cooling a hotfluid of a gas turbine engine. The directing the hot fluid through aplurality of cooling channels that are radially layered within theannular duct to define a heat transfer area; and passing a cooling fluidthrough the annular duct such that the cooling fluid passes between theradially layered cooling channels. For example, the cooling fluidgenerally flows through the annular duct in an axial direction of thegas turbine engine.

For example, FIG. 13 illustrates a cross-sectional view of oneembodiment of a gas turbine engine 310 including one or more annularheat exchangers 10. The position of the annular heat exchanger(s) may bevaried as desired, but is in particular embodiments within the coreengine 314. For instance, the annular heat exchanger can utilize fan air354 as the cooling fluid (either directly or routed into the annularduct), and the hot fluid can be bleed air from the core of the gasturbine engine. The gas turbine engine may be utilized within anaircraft in accordance with aspects of the present subject matter, withthe engine 310 being shown having a longitudinal or axial centerlineaxis 312 extending therethrough for reference purposes.

In general, the engine 310 may include a core gas turbine engine(indicated generally by reference character 314) and a fan section 316positioned upstream thereof. The core engine 314 may generally include asubstantially tubular outer casing 318 that defines an annular inlet320. In addition, the outer casing 318 may further enclose and support abooster compressor 322 for increasing the pressure of the air thatenters the core engine 314 to a first pressure level. A high pressure,multi-stage, axial-flow compressor 324 may then receive the pressurizedair from the booster compressor 322 and further increase the pressure ofsuch air. The pressurized air exiting the high-pressure compressor 324may then flow to a combustor 326 within which fuel is injected into theflow of pressurized air, with the resulting mixture being combustedwithin the combustor 326. The high energy combustion products aredirected from the combustor 326 along the hot gas path of the engine 310to a first (high pressure) turbine 328 for driving the high pressurecompressor 324 via a first (high pressure) drive shaft 30, and then to asecond (low pressure) turbine 332 for driving the booster compressor 322and fan section 316 via a second (low pressure) drive shaft 334 that isgenerally coaxial with first drive shaft 330. After driving each ofturbines 328 and 332, the combustion products may be expelled from thecore engine 314 via an exhaust nozzle 336 to provide propulsive jetthrust.

It should be appreciated that each compressor 322, 324 may include aplurality of compressor stages, with each stage including both anannular array of stationary compressor vanes and an annular array ofrotating compressor blades positioned immediately downstream of thecompressor vanes. Similarly, each turbine 328, 332 may include aplurality of turbine stages, with each stage including both an annulararray of stationary nozzle vanes and an annular array of rotatingturbine blades positioned immediately downstream of the nozzle vanes.

Additionally, as shown in FIG. 13, the fan section 316 of the engine 310may generally include a rotatable, axial-flow fan rotor assembly 338that is configured to be surrounded by an annular fan casing 340. Itshould be appreciated by those of ordinary skill in the art that the fancasing 340 may be configured to be supported relative to the core engine314 by a plurality of substantially radially-extending,circumferentially-spaced outlet guide vanes 342. As such, the fan casing340 may enclose the fan rotor assembly 338 and its corresponding fanrotor blades 344. Moreover, a downstream section 346 of the fan casing340 may extend over an outer portion of the core engine 314 so as todefine a secondary, or by-pass, airflow conduit 48 that providesadditional propulsive jet thrust.

It should be appreciated that, in several embodiments, the second (lowpressure) drive shaft 334 may be directly coupled to the fan rotorassembly 338 to provide a direct-drive configuration. Alternatively, thesecond drive shaft 334 may be coupled to the fan rotor assembly 338 viaa speed reduction device 337 (e.g., a reduction gear or gearbox) toprovide an indirect-drive or geared drive configuration. Such a speedreduction device(s) may also be provided between any other suitableshafts and/or spools within the engine 310 as desired or required.

During operation of the engine 310, it should be appreciated that aninitial air flow (indicated by arrow 350) may enter the engine 310through an associated inlet 352 of the fan casing 340. The air flow 350then passes through the fan blades 344 and splits into a firstcompressed air flow (indicated by arrow 354) that moves through conduit348 and a second compressed air flow (indicated by arrow 356) whichenters the booster compressor 322. The pressure of the second compressedair flow 356 is then increased and enters the high pressure compressor324 (as indicated by arrow 358). After mixing with fuel and beingcombusted within the combustor 326, the combustion products 360 exit thecombustor 326 and flow through the first turbine 328. Thereafter, thecombustion products 360 flow through the second turbine 332 and exit theexhaust nozzle 336 to provide thrust for the engine 310.

As stated, a hot fluid (e.g., bleed air) can be cooled in the annularduct of a gas turbine engine through the presently described apparatusand methods. In one embodiment, the hot fluid can be directed through aplurality of cooling channels that are radially layered within theannular duct to define a heat transfer area (e.g., defined within aplurality of layered curvilinear plates as described above), and acooling fluid can be passed through the annular duct such that thecooling fluid passes between the radially layered cooling channels.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they include structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal languages of the claims.

What is claimed is:
 1. A method of cooling a hot fluid in an annularduct of a gas turbine engine, comprising: directing the hot fluidthrough a plurality of cooling channels that are radially layered withinthe annular duct to define a heat transfer area; and passing a coolingfluid through the annular duct such that the cooling fluid passesbetween the radially layered cooling channels.
 2. The method of claim 1,wherein the cooling fluid is generally flowing through the annular ductin an axial direction of the gas turbine engine.
 3. The method of claim1, wherein at least 90% of the cooling fluid flows through the heattransfer area of the annular duct.
 4. The method of claim 1, wherein atleast 95% of the cooling fluid flows through the heat transfer area ofthe annular duct.
 5. The method of claim 1, wherein at least 99% of thecooling fluid flows through the heat transfer area of the annular duct.6. The method of claim 1, wherein the plurality of cooling channels aredefined within a plurality of curvilinear plates that are radiallylayered within the annular duct, and wherein each curvilinear platetraverses the annular duct from a radially inner portion to a radiallyouter portion.
 7. The method of claim 6, wherein a gap is definedbetween radially adjacent curvilinear plates through which the coolingfluid flows.
 8. The method of claim 1, wherein the cooling fluid is fanair of the gas turbine engine, and wherein the hot fluid is bleed air ofthe gas turbine engine.
 9. A method of cooling a hot fluid in an annularduct of a gas turbine engine, comprising: directing the hot fluidthrough a plurality of cooling channels that are radially layered withinthe annular duct to define a heat transfer area; and passing a coolingfluid through the annular duct in an axial direction of the gas turbineengine, wherein at least 90% of the cooling fluid flows through the heattransfer area of the annular duct.
 10. The method of claim 9, wherein atleast 95% of the cooling fluid flows through the heat transfer area ofthe annular duct.
 11. The method of claim 9, wherein at least 99% of thecooling fluid flows through the heat transfer area of the annular duct.12. The method of claim 9, wherein the plurality of cooling channels aredefined within a plurality of curvilinear plates that are radiallylayered within the annular duct, and wherein each curvilinear plate issupported structurally so that thermal expansion of each curvilinearplate relative to the annular duct is unrestrained in at least onedirection.
 13. The method of claim 9, wherein the cooling fluid is fanair of the gas turbine engine, and wherein the hot fluid is bleed air ofthe gas turbine engine.
 14. A method of cooling a hot fluid in anannular duct of a gas turbine engine, comprising: passing the hot fluidinto a first inner radial tube, through a plurality of cooling channelsdefined within a plurality of curvilinear plates that are radiallylayered within the annular duct, and into a second inner radial tube;and passing a cooling fluid through the annular duct.
 15. The method ofclaim 14, wherein each curvilinear plate comprises an inner platedefining a plurality of first grooves and an outer plate defines aplurality of second grooves, wherein the outer plate is attached to theinner plate with the plurality of first grooves and the plurality ofsecond grooves substantially aligned to define a plurality of channelstherebetween.
 16. The method of claim 14, wherein each cooling channeldefines a nonlinear path having at least one curve extending from afirst opening through the curvilinear plate to a second opening, whereinthe first opening is in fluid communication with the first inner radialtube, and wherein the second opening is in fluid communication with thesecond inner radial tube.
 17. The method of claim 14, wherein eachcurvilinear plate further comprises an integral wall positioned betweenthe inner plate and the outer plate such that the hot fluid passesthrough a first passageway and a second passageway within the pluralityof channels.
 18. The method of claim 17, wherein the outer plate of eachcurvilinear plate defines a chord length measured as a shortest distancefrom a first end to a second end, and wherein the outer plate defines anarc length measured across its outer surface from the first end to asecond end, and further wherein the arc length is about 105% to about150% of the chord length.
 19. The method of claim 14, wherein thecooling fluid is fan air of the gas turbine engine, and wherein the hotfluid is bleed air of the gas turbine engine.
 20. The method of claim14, wherein at least 90% of the cooling fluid flows through a heattransfer area of the annular duct defined radially outward from thefirst inner tube and the second inner tube to an outer supportstructure.